+PRODUCTIVITY, +SMOOTHNESS, +DENSITY

CAT® SDX SCREED PLATE SYSTEM DELIVERS RESULTS

Central Specialties, Inc. of Alexandria, Minnesota recently completed a 10.53-mile segment of North Dakota Highway 85 in McKenzie County from Watford City south to the Long X Bridge. Accounting for approximately 65% of the contract’s $77.23 million value, major categories included some pavement removal, common excavation, borrow excavation, drainage piping, placement of an 18-inch aggregate base course for the new roadway, asphalt paving, and topsoil placement. The project’s timeframe extended from April 1, 2023 through October 5, 2024, with a five month winter work suspension from November 15, 2023 to April 15, 2024.

The contract specified placement of a 3.5-inch asphalt overlay on the existing two-lane roadway, while the new, two lane segment involved placement of an 18-inch crushed stone base supporting 7.5 inches of new asphalt. Some segments were divided, and some were not. Pavement bonus payments were available for asphalt compaction

CAT® SDX SCREED PLATE PERFORMANCE

“I’ve observed many asphalt-paving innovations during my 22 years in the business, and these Cat SDX Screed Plates rank right up there near the top of the most-impressive list,” noted paving superintendent John Fales. “We’ve been using them for more than a year now. When we first started, we quickly noticed the uncompacted mat behind the screed was much denser. When we walked on the uncompacted mat, we weren’t leaving footprints. That in itself was very impressive and convinced us the this technology was for real.

“Over time, we also observed the metallurgy used in the SDX Screed Plates were helping them last much longer, six, seven, or eight times longer. That’s impressive, particularly when you consider that we’re dealing with very jagged, crushed granite and quartzite. With these drier aggregates we’re seeing here in North Dakota, we’ve also been able to run the pavers as fast as 90 feet per minute. Productivity is up. Smoothness is up. And density behind the screed is up. And compacted density across the mat is more consistent. What we’ve noticed the most is a denser, tighter wear surface, plus we’re not seeing nearly as much roller squish-out.

“The kneading action through and below the the Cat SDX Screed Plates that the Cat Paving guys like to talk about really helps lay down a tighter, denser mat. The density behind the screed is consistently higher than we normally see with conventional screed plates. Squeezing out the voids definitely helps with increased quality in four key areas: density, smoothness, resistance to moisture penetration, and wear surface longevity. We can lay an inch and a half compacted mat containing three-quarter (inch) rock, and you’re not going to see segregation like you would with traditional plates. The screed plates might be eliminating as much as 95% of the segregation that we see on some jobs. The longer I’ve seen the new screed plate in action, the more impressed I’ve become with the results.

“When it comes to longevity, these SDX Screed Plates are really tough. In highly abrasive material, we’ve sometimes had to replace conventional plates at less than 50,000 tons. The SDX plates went 300,000 tons, and upon removal and replacement, we discovered we could have used them even longer with no impact on paving quality. The wear longevity has become a key selling point for us. All things considered, what’s not to like about the SDX Screed Plates?

“Plus, we always receive topnotch parts and service support from Ziegler Cat and from other Cat dealers when we’re working outside Minnesota. That’s a given and a key aspect of what separates Cat machines from other brands. Wherever we work across the upper Midwest and Plains states, Cat dealer support is always a positive. In our home state of Minnesota, Ziegler is particularly outstanding. We rely on them for parts, field service, shop service, rebuilds, trade-ins, equipment financing, and more.”

Additional Cat SDX Commentary

Additional commentary was provided by Carlos Pasillas. He’s been with Central Specialties more than 10 years, the last seven as a screed operator. “The mat behind the SDX screed definitely has a different Cat look with the horizontal lines, but you quickly understand the uncompacted density behind the screed is much better. Depending somewhat on the mix design, we’ve hit pre-compaction densities as high as 90, 91, and even 92%. That’s unheard of with a conventional screed.

“I’ve also found joint matching to be much easier with the SDX plates. You can just set it and go. It’s much easier than the conventional screed, requires less adjusting. We’re consistently laying down mats that are closer to the target density. The transition process to the SDX screed involved a fairly short learning curve. Within two weeks, we had it figured out and dialed in. Given a choice, I definitely prefer the SDX Screed Plates. The mat’s a lot smoother, we see fewer segregation problems, and the density behind the screed is significantly better.”

This commentary wouldn’t be complete without hearing from a member of the compaction team. Central Specialties lead operator Brad O’Brien is a 22-year asphalt paving veteran. He runs one of the Cat CB15 rollers behind the paver equipped with the Cat SDX Screed Plate.

“I really like the SDX. At first, it felt different. However, the results quickly proved it’s a better screed system. I backed off on using the double drums. Now I’m mostly rolling with a single drum. Basically, I make longer passes with fewer stops. I use less water. The mat holds heat really well. If I encounter any bumps in the mat, I can blow through them, and they’re gone. Even if the paver is running at higher feet per minute, the compaction team has no trouble keeping pace and meeting or exceeding the target density specs.

“When I first started rolling behind the Cat SDX Screed Plates, I immediately felt the mat was denser. The effort, the energy needed to achieve final compaction is considerably less with these new plates. That’s true whether counting the number of passes, double versus single drum, or static versus vibe. The rolling team is working to determine to what extent the breakdown, intermediate and/or finish pass counts can be reduced in various circumstances. We really like Cat pass mapping. It helps us see exactly where we’re at and where we’ve been.”

The challenging scope, harsh working environment, and complexity of this turnkey Highway 85 segment thoroughly tested the Central Specialties team, their machines, as well as all of the federal, state, regional and local oversight and support staff. Suffice it to say that everyone and everything involved on the Highway 85 project, including the new Cat SDX Screed Plate System, exceeded expectations.

Caterpillar. (2024). CAT® SDX screed plate system delivers results for Central Specialties on Highway 85. Caterpillar Inc. https://s7d2.scene7.com/is/content/Caterpillar/CM20250318-35042-8f862